The present invention relates to pointing devices and, more particularly, to a pointing device having a plurality of motion sensors to determine rotational movement of the pointing device relative to an object.
A pointing device (sometimes referred to as a xe2x80x9cmousexe2x80x9d) is used to move an image, such as a cursor, on a video monitor as the pointing device is moved relative to a fixed object, such as a mouse pad. A motion sensor in the pointing device detects the movement of the pointing device relative to the object and generates data corresponding to the relative movement. The data is transmitted to a processor associated with the pointing device and the video monitor. Based on the data, the processor causes the image to move proportionally to the movement of the pointing device relative to the object. The pointing device may also be used to move complex images displayed on the video monitor, such as images associated with computer aided drafting programs.
Some pointing devices have a ball that extends from a surface on the pointing device to contact the object. As the pointing device is moved relative to the object, the ball rotates accordingly. A sensor within the pointing device measures the rotation of the ball. For example, the sensor typically measures an x-component and a y-component of the ball rotation. The x and y-components of the ball rotation correspond to x and y movements of the pointing device relative to the object. The sensor generates data corresponding to the ball rotation and transmits the data to a processor that is associated with the pointing device and the video monitor. The processor displays an image on the video monitor and causes the image to move proportionally to the ball rotation data. Accordingly, the image moves proportionally to the movement of the pointing device relative to the object.
Some pointing devices have position sensors that use optical devices. In one example of such a pointing device, the pointing device is placed on a surface that has specifically placed grid lines extending in an x-direction and a y-direction. The pointing device has an optical sensor attached thereto that detects the grid lines. As the pointing device is moved relative to the grid lines, the optical sensor generates data corresponding to the x and y movement of the pointing device relative to the surface. As was described with relation to the ball-type pointing device, a processor translates the movement of the pointing device into movement of an image, such as a cursor, on the video monitor.
Both the ball-type and the optical-type pointing devices have several disadvantages. Both pointing devices only generate data corresponding to the x and y movements of the pointing device relative to the object. Neither pointing device generates data corresponding to the rotation of the pointing device relative to the surface. Accordingly, neither pointing device is capable of causing an image displayed on the video monitor to rotate as the pointing device is rotated. Thus, when the cursor is used to manipulate images displayed on the video monitor, the images are unable to be rotated proportional to the rotation of the pointing device. Other commands, such as keyboard functions have to be used in order to rotate the images, which tend to be cumbersome. Another disadvantage of many optical-type pointing devices is that they may only be used on a surface with appropriate grid lines. If such a surface is not available or if the grid lines have deteriorated, the pointing devices are rendered inoperable.
A ball-type pointing device has disadvantages in that contaminants adversely affect its operation. For example, oils and other friction reducing chemicals may reduce the friction between the ball and the object. As the pointing device is moved relative to the object, the ball slides instead of rotating relative to the object. Accordingly, the pointing device is not able to generate data corresponding to its movement relative to the object. This results in the image not being able to move properly on the video monitor per the movement of the pointing device relative to the object. Another problem with ball-type pointing devices is that contaminants interfere with the motion sensors and cause corrupt data to be generated. This corrupt data, in turn, causes the image to move disproportionally relative to the movement of the pointing device. An optical-type pointing device is also susceptible to contamination. For example, if contaminants are located on the grid, the optical sensor may detect them as grid lines. The position data generated by the pointing device will then be inaccurate, which ultimately causes the movement of the image on the video monitor to be inaccurate.
Therefore, a need exists for a pointing device that overcomes the above-described problems and that is capable of generating data that causes an image displayed on a video monitor to rotate.
The present invention is directed toward a pointing device (sometimes referred to as a xe2x80x9cmousexe2x80x9d) that uses optical sensors to generate data corresponding to its movement relative to an object. The data corresponds to conventional movement in the x and y-directions in addition to data corresponding to the rotation of the pointing device relative to the object. The pointing device may comprise a housing having a first navigator and a second navigator located therein. The navigators may be two-dimensional photosensor arrays that generate image data representative of two area portions of the object. The object may, as examples, be a mouse pad or a sheet of paper.
The pointing device is electrically connected to a computer, which in turn is electrically connected to a video monitor. The computer analyzes the image data generated by the navigators to determine the movement of each navigator relative to the object. For example, if the object is a sheet of paper, the navigators generate image data representative of the surface features of the sheet of paper. As the pointing device moves relative to the sheet of paper, the surface features move relative to the navigators. By analyzing the movement of the surface features relative to the navigators, the motion of the pointing device relative to the object may be readily determined. The use of the two navigators further provides for the rotational motion of the pointing device relative to the object to be readily determined. For example, rotational movement of the pointing device may be derived from the difference in movement data generated by the two navigators.
The computer causes a cursor or other image to be displayed on the video monitor. As the pointing device is moved relative to an object, the cursor or other image displayed on the video monitor may move proportionally to the movement of the pointing device relative to the object. The pointing device disclosed herein provides rotational movement data to the computer. Accordingly, rotation of the pointing device may cause the cursor or other image displayed on the video monitor to rotate.